GIT_SHALLOW_FILE_ENVIRONMENT 1618 builtin/receive-pack.c 	setenv(GIT_SHALLOW_FILE_ENVIRONMENT, alt_shallow_file, 1);
GIT_SHALLOW_FILE_ENVIRONMENT  117 environment.c  	GIT_SHALLOW_FILE_ENVIRONMENT,
GIT_SHALLOW_FILE_ENVIRONMENT  185 environment.c  	shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);